This invention relates generally to injection molding and more particularly to a hot tip torpedo molded of a carbide alloy to be seated in the front end of a heated nozzle in alignment with a gate.
As seen in Mold-Masters Limited brochure entitled "DURA Hot Runner Systems" dated September 1995, hot tip torpedoes having a melt channel with a diagonal front portion extending to an outlet on a conical front surface are already known. However, the melt channel of these previous torpedoes is not tapered and they are made of copper alloy plated or other very conductive materials by conventional machining. While they are satisfactory for some applications, they have the disadvantages that these materials are sufficiently resistant to corrosion and wear from the pressurized melt flowing therethrough.
It is also known that carbide alloys are more resistant to corrosion and wear than these other materials. However, carbide alloys are very difficult to machine, and it would be prohibitively expensive to machine these previous torpedoes of a carbide alloy. Using a M/M (metal injection molding) process to make metal products by injection molding the powdered metal in a molten liquid form and then debinding and sintering the product is also known. However, making these previous torpedoes by injection molding is impossible because their shape would prevent ejection from the mold.